7
3. Operation
3.1 Keyboard and display
The Mark 25 front panel consists of a
4 digit red LED display, 3 parameter and
channel LED’s, an alarm LED, and an 8-
key keypad. The display is used to
present all parameter measurements,
operator prompts and system errors.
The keys are arranged in two rows, four
keys in each row.
The
top row
of keys
consist of three
color-outlined
function keys
and are
used to perform instrument operations
such as selecting which parameter to
view, what range the parameter is to be
viewed in, parameter calibration and
system set up.
The
bottom row of keys
are multi-
colored, multi-legend keys and are used
in conjunction with the function keys.
The same colored legends correspond
to the same colored function key.
The
arrow keys
are used to view
channels, select functions during setup
and calibration, and increment or
decrement a displayed value.
READ key
- When the <READ> key is
pressed, the Mark 25 will display
rd
. If
one of the bottom keys is selected, the
parameter high-lighted in red will be
displayed and its corresponding LED lit.
RANGE key
- Range changes can be
made manually for raw conductivity and
temperature-corrected conductivity only.
To change the range, press the
<RANGE> key, then select
either LOW, MED, or HIGH to display
the desired range. If the Mark 25 is
setup for auto-ranging, the Mark 25 will
display
AUrg
as long as the <RANGE>
key is pressed.
NOTE:
Manually changing the range for
temperature-corrected conductivity
changes the analog recorder output
scaling.
See Section 3.7 for details
.
Viewing a different channel
is easily
done by pressing the <UP> or <DOWN>
arrow key. The parameter LED’s to the
left of the Mark 25 display also indicate
which channel is being viewed. Channel
ID’s are as follows:
Red
LED - Channel 1
Green
LED - Channel 2
Red/Green
LED - Channel 3
Flashing Red
LED - Channel 4
3.2 The CALIB key
All setup and calibration functions are
conducted via the <CALIB> key. The
<CALIB> allows you to set the following:
READ
Range
CALIB
LOW
o
C
ZERO
MED
RAW
SPAN
HIGH
TC
RUN
